1. Field of the Invention
The invention relates to metal founding. More particularly, the invention relates to centrifugal casting liquid metal. More particularly the invention relates to forming a composite article incorporating particulate matter.
2. Discussion of the Related Art
Light weight internal combustion engines have necessitated the use of aluminum and aluminum alloys for engine cylinder blocks, cylinders and cylinder heads. To make up for the deficiencies in physical properties of aluminum and aluminum alloy engines, working surfaces have been coated with materials with better physical properties to improve working life and performance of the engines. Specifically, the inner surface of cylinders has been coated with a hard inner layer to improve wear performance. In the alternative, a hard face liner/sleeve is inserted into cylinders for the same purpose.
The hard inner layer can be applied by metal matrix composite (MMC) casting a silicon carbide (SiC) layer on the cylinder surface to form a composite. This is done by weaving a cylindrical structure of silicon carbide (SiC) fibers and pressure casting with aluminum alloy. The process is used primarily for racing engines where performance is a greater concern than cost.
Centrifugal casting is a less costly method of forming cylindrical parts. Centrifugal casting has been used to cast aluminum and aluminum alloy parts in combination with particulate matter to improve physical properties of the engine part. There are four requirements for a particle to be successful for inner surface hardening of aluminum by centrifugal casting. First, the particle must be hard compared to the hardness of the aluminum or aluminum alloy. Second, the particle must have a density lower than that of liquid aluminum. Third, the particle must have a significantly higher melting temperature than that of aluminum or aluminum alloy. Fourth, the particle must be able to wet the aluminum without dissolving or significantly reacting with it.
These requirements have not been fully met by methods and materials used in the art.